(a) Field of the Invention
This inventive concept relates to semiconductor technology, and more specifically to a semiconductor device and its manufacturing method.
(b) Description of the Related Art
The DC amplification factor (β) of a Bipolar Junction Transistor (BJT) is proportional to the width of its emission region, and inversely proportional to the width of its base region. Typically, a wide emission region can be obtained by a high-energy or high-dose ion implantation process. However, a high-energy or high-dose ion implantation process can also lead to high density of crystal defects in the base region, and cause leakage current or even short circuit between the emission region and its collection region.
In most semiconductor circuits or devices, BJT is a parasitic device. For example, it could be a parasitic device located beside a Metal Oxide Semiconductor (MOS) device. Therefore, the widths of its emission region and base region are limited in the MOS device, and optimizing their widths would require additional hard mask and could adversely affect the overall performance of the MOS device.